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x86/sev-es: Do not unroll string I/O for SEV-ES guests

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Under the GHCB specification, SEV-ES guests can support string I/O.
The current #VC handler contains this support, so remove the need to
unroll kernel string I/O operations. This will reduce the number of #VC
exceptions generated as well as the number VM exits for the guest.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/3de04b5b638546ac75d42ba52307fe1a922173d3.1612203987.git.thomas.lendacky@amd.com
This commit is contained in:
Tom Lendacky 2021-02-01 12:26:27 -06:00 • committed by Borislav Petkov
parent 1048ba83fb
commit 62a08a7193
1 changed files with 3 additions and 2 deletions
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5
arch/x86/mm/mem_encrypt.c
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@ -474,9 +474,10 @@ void __init mem_encrypt_init(void)
swiotlb_update_mem_attributes(); swiotlb_update_mem_attributes();
/* /*
* With SEV, we need to unroll the rep string I/O instructions. * With SEV, we need to unroll the rep string I/O instructions,
* but SEV-ES supports them through the #VC handler.
*/ */
if (sev_active()) if (sev_active() && !sev_es_active())
static_branch_enable(&sev_enable_key); static_branch_enable(&sev_enable_key);
print_mem_encrypt_feature_info(); print_mem_encrypt_feature_info();